Fidelity of Biodynamic Simulation Models for Low Speed Collinear Rear Crash Conditions 2012-01-0570

Dynamic simulation is routinely used to analyze the occupant response to motor vehicle impact. That said, while commercially-available models have been subjected to numerous high-severity level validation studies, little attention has been given to lower severity crashes. While high severity crashes typically result in more severe injury, the vast numbers of lower severity “fender bender” type crashes and the ensuing high medical costs warrant study related to biomechanics and vehicle design. The scope of this study is directed at addressing the validity of these models for analyzing occupant response to collinear rear impact involving delta-V less than 5 mph. As part of this study, a series of five vehicle-to-vehicle collisions with instrumented volunteer occupants were performed with closing speeds of 1.1, 1.9, 2.9, 4.0 and 5.1 mph. These impacts produced delta-V, for the target vehicle, of 0.6, 1.8, 2.5, 3.1 and 3.2 mph, respectively. The measured response of the volunteer kinematics was compared with GATB simulation. Overall, the average percent discrepancy between the measured test data and the simulated values was 7.2 percent. With the exception of four instances, the percent discrepancy between the measured and simulated occupant response for each individual parameter was less than 10 percent. For the four instances where the difference between the measured and simulated values was greater than 10 percent, the simulated response consistently over-estimated the actual measured value in each case. Further, in the instances where the simulated response demonstrated and under-estimate of the measured value, the differences were small, exhibiting an average percent discrepancy of 4.3 percent. In addition, a parametric study of the influence of seat cushion stiffness to peak occupant response, demonstrated low sensitivity. Specifically, increasing the seat cushion stiffness 300 percent produces just a 22 percent increase in peak head acceleration. Similarly, the same seat cushion stiffness increases lead to increased peak chest and lumbar responses of 10 and 25 percent, respectively.